Patent GB-817006-A (GB)
Title: An improved control system for turbine driven machines
IPC: F01D21/02
Filed: 1955-10-04
Abstract: 817,006. Turning-gear. GENERAL ELECTRIC CO. Oct. 4, 1955 [Oct. 11, 1954], No. 28254/55. Class 7(5) [Also in Groups XII, XXI and XXVI] A control system for a turbine type starter motor having a gear train between the turbine rotor and the engine being started, comprises means for supplying motive fluid to the turbine rotor at two levels of energy or at two different rates and consequently pressures; means for initiating a flow of motive fluid at a first low level of energy content or at a low rate and pressure to the turbine rotor, the motive fluid being such that the turbine rotor cannot overspeed even when unloaded and means responsive to the transmission of power through the gear train to initiate the flow to the turbine rotor of fluid at a second higher level of energy content or at a higher rate and pressure when a predetermined torque is attained. The turbine rotor 6, Fig. 1, is supplied with motive fluid from a combustion chamber 18 through an inlet 2 and nozzle box 3. The turbine drives through helical gears 9, 10 and a unidirectional clutch 24 an engine 25. The output shaft 11 which carries the gear 10 is mounted so as to permit axial movement of the shaft with respect to the casing 42 on which is mounted normally open contacts 13 of an electrical switch. A contact arm 14, which may engage the contacts 13, is carried by a stem 40 urged by a spring 12 against the end of the shaft 11. The shaft 11 is also urged away from the turbine rotor 6 so that the arm 14 is away from the contacts 13. The combustion chamber 18 is supplied with air or other combustion supporting fluid from a storage bottle 22 through a conduit 20 controlled by a valve 21. Fuel is supplied from the container 30<SP>1</SP> to the combustion chamber through a conduit 17 containing a control valve.17 biased to the closed position and which may be opened by energizing the solenoid 19. To start the turbine 6, the valve 21 is opened. Air flows to the turbine which then begins to rotate. When the clutch 24 is engaged torque is transmitted through the gears 9, 10 which causes the shaft 11 to move against the action of the spring 12 and the contact arm 14 to bridge the contacts 13. The solenoid 19 is then energized and the valve 16 opened. Fuel flows to the combustion chamber where it is ignited. A large turbine output is then available to accelerate the engine 25. If, for any reason, the turbine 6 is disengaged from the engine 25, negligible torque is transmitted through the gears 9, 10 and the spring 12 will urge the shaft 11 to the left and break the connection between the arm 14 and contacts 13. The solenoid 19 will be deenergized and the valve 16 closed. In a modification, Fig. 3, the turbine motive fluid is supplied by a cartridge comprising a reloadable breech containing two charges 27, 28. The charges are located in portions of the breech separated by a one-way blow out member 34 which is constructed so that it will rupture in response to a relatively low pressure in the part of the breech containing the charge 27 but will not rupture easily in response to pressure in the other part of the breech. On closure of the switch 33, squib 30 is energized to ignite the charge 28 which then supplies working fluid to the turbine 6 through the conduit 31. When the switch 13 is closed due to transmission of torque through the gears 9, 10 squib 29 is energized and charge 27 ignited. Member 34 is then ruptured and a further large quantity of gas supplied to the turbine 6. The single stage reduction gear train 9, 10 may be replaced by a multiple stage gear train. Specifications 768,492 [Group XXIV] and 770,991 are referred to.